Multimedia streams, which typically include video frames, are compressed prior to transmission, to conserve bandwidth. Compressing video generally means representing a relatively larger group of bits with a relatively smaller group of bits.
When a video frame or frames contains a symbol, generally used herein to refer to both graphics symbols and alpha-numeric characters, the bits representing the symbol are compressed along with the bits representing the image. That is, when video is overlaid with graphics or alpha-numeric symbols, both the underlying image and the symbols are compressed together for transmission. Upon receipt, the stream is decompressed to render a “lossy” version of the original image.
The present invention understands that compressing and decompressing a multimedia stream, while critical to the efficient transmission of multimedia, often results in some lost data. As a result, some useful information in the original stream might not reappear in the decompressed stream. The present invention further understands that in the context of video images, losing a small amount of information usually is of small consequence, since a viewer will be unable to detect the loss in the relatively large volume of data that makes up a video image.
The present invention critically recognizes, however, that symbols generally do not require much data to render. Consequently, losing a small amount of symbol information during the compression/decompression process can result in detectable distortions and/or artifacts in the decompressed symbol. Furthermore, having to compress and transmit symbols along with the images to which they pertain consumes multimedia transmission bandwidth.
In addition to the above recognition, the present invention understands that transmission of images over wireless links to portable devices often necessitates a significant reduction in resolution. Reduced resolution means there are fewer pixels available for representing a symbol. The small display screens commonly used on mobile devices limits the ability of the human visual system, or HVS, to easily and accurately discern symbols. The present invention understands that being able to enlarge or transform symbols in video that is displayed on small screens would improve the ability of the HVS to discern the symbols. With these observations in mind, the invention below is provided.